This invention relates to electrochemical processes and, in particular, to a method and apparatus for improving such processes.
Electrochemical processes can either be faradaic or non-faradaic where, in faradaic processes, the cell reactions are governed by Faraday's law and in non-faradaic processes, they are not. Faradaic reactions may either be galvanic (cell reactions occur spontaneously at the electrodes when they are connected externally by a conductor) or electrolytic (cell reactions are effected by the imposition of an external voltage greater than the reversible potential of the cell). Examples of galvanic processes include primary cells, secondary cells, fuel cells (e.g., an H.sub.2 --O.sub.2 cell), etc. while examples of electrolytic processes include electrolytic synthesis (e.g., the production of chlorine and aluminum), electrorefining (e.g., copper), electroplating (e.g., silver and gold), etc. Recharging of a secondary cell may also be an electrolytic process. See "Electrochemical Methods" by A. Bard and L. Faulkner, 1981, John Wiley & Sons, New York for a further discussion of electrochemical processes in general.
One known source, and probably the most significant source of wasted energy, in electrochemical processes (faradaic and non-faradaic) is the electric double layer which tends to form at at least one of the electrodes of an electrochemical cell.
It is a primary object of this invention to provide an improved method and apparatus for lessening the effect of the electric double layer in electrochemical processes and thus enhancing the performance of such processes.
A battery charger is, of course, one well known device for improving the performance of a galvanic process where, as indicated above, such chargers may involve only an electrolytic process--that is, if the current direction through the electrolyte is only in the direction opposite to the current direction when the cell functions as a battery, only an electrolytic process is involved. This is typical of most battery chargers and little, if anything, is done to lessen the effect of the electric double layer on the charging process. Moreover, sulphanation of the electrodes tends to occur in such unidirectional chargers.
In one known process described in an article (copy submitted herewith) entitled "Investigation of Charging Methods for Nickel-Cadmium Batteries", by O. Wagner and D. Williams, there is described a charger in which a current pulse is applied in the charging direction and then a further current pulse is applied in the reverse direction. This procedure is repeated until the theoretical energy inputted is the battery capacity. However, in this process, the amount of current applied both during the charging pulse and the reverse current pulse is determined by the charging device connected to the battery.
It is thus a further object of this invention to provide an improved method and apparatus for improving the performance of electrochemical cells where the cell itself plays a significant role in determining the current it needs to effect efficient electrode repolarization, lessening or removal of the electric double layer, and exercising of the electrolyte to thus substantially enhance cell performance.
Other objects and advantages of this invention will be apparent from a reading of the following specification and claims taken with the drawing.